Assigitoe



J. H. AYOTTE.

SPARK PLUG.

APPLICATION FILED JULY 19, 1919.

l ,3 6 3, 2 1 2 Patentedy Dec. 28, 1920.

UNITED STATES PATENT oFFlcE.

JOSEPH REN AYOTTE, OF CHICAGO, ILIIZIISTOXS` ASSIGNOR OF ONE-HALF TOJULES X.

RIVARD, 0F CHICAGO, lLLINOIS.

SPARK-PLUG'.

Specification of Letters Patent. Patented Dec. 28, 1920.

Application filed July 19, 1919. Serial No. 311,961.

To all @rho/m it may concern Be it known that I, JOSEPH REN AYOTTE, asubject of the King ot Great Britain, residingl at Chicago, in thecounty of Cook and State ot Illinois, have invented certain new anduseful Improvements in Spark-Plugs, oi" which the following is aspecification.`

My invention relates to spark plugs.

One of the objects ot the invention is to provide, preferably, a dualspark-gap plug in which separation between the electrodes, constitutingthe spark gap, will remain unchanged under varying changes oi'temperature oit the plug; which is so constructed that very little heatis conducted from the central conductor to the unsupported end of theporcelain core, thereby avoiding spontaneous fracture or crizzling ofthe vitreous coating of the porcelain core, due to diiter* ences ottemperature between the exterior and the interior surt'ace of the core,when exposed to sudden drafts of air or drenching by water, or the like.

Still another object is to provide means whereby the length of theinterior, or intensifying spark-gap will invariably be and remain otuniform length without being aftected by the act ot assembling theparts.

Other, further and more particular objects oit the invention will becomereadily apparent, to persons skilled in the art, from a consideration otthe following description when taken in conjunction with the drawings,wherein- Figure 1 is a central axial section.

Fig. 2 is an inverted plan View.

3, 4. and 5 are views of modified parts.

1n all the views the same reference characters are employed to indicatesimilar parts.

Referring to the structure shown in Figs. 1 and 2, 6 is .the usualthreaded shell for containing the core 7. It is threaded, as at 8, andcontains the lower electrode 9, which is secured to the lower annular,salient end of the shell, as usual in devices of this kind. One of thepeculiar features oi' this portion of the device, however. is the bend,as at 10, between the vertical part 9 and the horizontal part 11, togive greater strength to the electrode.

A central conductor 12 passes through an enlarged axial-opening 13 andis cemented therein by cement 14. Concentric with the opening 13 is alarger opening or cavity 15,

extending from near the end 16 of the core to a transverse plane near.the top of the shell. The central conductor 12 is bent into a sinuousor double curve, as at 17, having parts 18 and 19 that extend laterallyfrom themain portion 12 of the central conductor. Cemented in theopening 15 is the clamping structure 20 having a sleeve-like part 21 tobe cemented in the opening 15 by cement 22, and having a coaxiallyarranged threaded stem 23 projecting thereabove, for a clamping nut 241.The sinuous end 17 of the conductor 12 has its parts 18 and 19 in closerproximity to the interior of the sleeve 21 so that the spark will alwaysspring between one or both of these parts and the interior of thesleeve. Increased heat tending to cause expansion and elongation of theconductor 12, does not change'the relation be tween the parts 18 and 19and the interior et the sleeve, as the distance between these partsremains constant irrespective of the length of the conductor 12, withinthe limit of the device. The upper end of the conductor, which isfurther removed from the interior of the sleeve 21, is not a terminal ofa spark gap, as usual in structures o1 this character. The air contentof the sleeve 21 provides ample heat insulation between the conductor 12and the surrounding porcelain core 7, thereby preserving the upperportion of the core relatively cool. When the sleeve 21 is placed in theopening 15 the upper end of the conductor 12 may be entirely disregardedand the parts 18 and 19 oli' the central conductor will be in closeproximity to the sleeve so that the spark will take place between eitherof these parts and the interior of the sleeve, and the length of thisgap can be depended upon to be of uniform extent, as the verticalmovement of the sleeve 21 has no eilect to increase or decrease thedistance between the electrodes bounding the spark gaps. When it isdesired to do away with the intensifying spark gap, and use other partsof the structure, the sinuous part 17 may be bent, as clearly shown inFig. 4, whereby the parts 18 and 19, or either part, may be brought intoactual contact with the interior of the sleeve so that there will be nospark within the interior of the sleeve, as in the irst illustration.The springiness or resiliency of the central conductor 12 will besutlicient to maintain the parts in contact and anytendency toelongation of the central conductor will have the effect of increasingthe actual metallic contact between the parts 18 and 19 and the interiorof the sleeve, as any material relative movement will keep thecontacting parts bright and in good conducting condition.

In Fig. 4 I have shown an annular groove 25 in the part 20 to present alarger air radiating surface to disperse such heat, above atmosphere, asmay be imparted to this part of the structure. In Fig. 4 I have shownthe outside of the sleeve 21 to be threaded, so that cement will morereadily stick to'it so that it will be held more readily in the cavity15, when cement is applied. In Fig. 5 I have shown the same sleeve to beknurled, as at 26, for the same purpose,.

whereas in Fig. 3 separated grooves 27 are placed in the sleeve withinwhich cement may be placed in the act of cementing the of the conductorwithin the striking distance of the interior of the sleeve Within whichit is contained, and while Ihave shown several modifications of thisportion of the spark plug structure having the outer surface of thesleeve roughened .or otherwise made uneven to increase the tenaciouseffect of the cement therewith, it will be manifest that other forms mayandwill be suggested to persons skilled in the art, for accomplishingthis purpose.

` lVhile I have herein shown a single embodiment of my invention withseveral modifications, for the purpose of clear disclosure, it will bemanifest that other forms and variations in configuration anddisposition of the vparts is within the scope of the appended claims.

Having described my invention, what I claim is l. A spark plug having incombinative association an insulating core, a sleeve of conductingmaterial within the core, and forming one electrode of a spark gap and aconductor projecting into said sleeve in near proximity to the interiorsurface thereof between which and said conductor to produce the abruptdischarge that forms the spark.

2. A spark plug having in combinative association, a sleeve ofconducting material directly connected to one terminal of the plugforming one electrode of a spark gap and a central conductor projectinginto said sleeve having a plurality` of surface parts in near proximityto the interior surface of the side wall of the sleeve between one ofwhich parts and the sleeve to produce the abrupt discharge which formsthe spark.

A spark plug having in combinative` association, a core, axiallyperforated for a central conductor, the upper end of the perforationterminating in an enlarged concentric cavity; a sleeve within thecavity, carrying a wire clamping part whereby to constitute oneelectrode of a spark gap and a central conductor having its upper endwithin the sleeve, forming the other electrode of said spark gap andforming an electrode for another spark gap at the lower end of the plug.

4. A spark plug having in combinative association a core provided in itsupper end with an enlarged cavity and an axially extending perforationcommunicating therewith; a sleeve cemented in said cavity, having on itsupper end a screw threaded stem, said sleeve constituting one electrodeof a spark gap; a central conductor in said core, having its upper endbent to bring a part thereof, intermediate its ends, nearer' the sleeve,constituting the other electrode of the spark gap and two electrodes atthe lower end of the plug of which the central conductor constitutes oneof the latter electrodes.

In testimony whereof I hereunto subscribe my name.

JOSEPH REN AYOTTE.

